如何构建一个Springd引导jar文件，systemd可以直接将其作为服务执行？

遵循 Installation作为systemd服务中
的示例，我创建了以下systemd服务，该服务 直接执行Spring Boot jarfile ：

[Unit]
Description=CRS Self-certification Service
Documentation=
Requires=postgresql.service
After=postgresql.service

[Service]
Environment=LOADER_PATH='lib/,config/,/etc/opes/crs/selfcertification'
ExecStart=/opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar
Restart=always
RestartSec=10
User=crs

[Install]
WantedBy=multi-user.target

但是，启动此服务时，systemd抱怨jarfile不可执行：

Nov 29 10:57:59 ubuntu systemd[24109]: selfcertification.service: Failed at step EXEC spawning /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar: Exec format error
Nov 29 10:57:59 ubuntu systemd[1]: selfcertification.service: Main process exited, code=exited, status=203/EXEC
Nov 29 10:57:59 ubuntu systemd[1]: selfcertification.service: Unit entered failed state.
Nov 29 10:57:59 ubuntu systemd[1]: selfcertification.service: Failed with result 'exit-code'.

jarfile的权限为755（所有人均可执行）：

administrator@ubuntu:~$ ls -la /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar
-rwxr-xr-x 1 crs selfcertification 35978778 Nov 22 17:16 /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar

为了为systemd服务构建可执行的jarfile，必须对以下Gradle构建脚本进行哪些更改？

buildscript {
    ext {
        springBootVersion = '1.4.2.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

jar {
    baseName = 'crs-selfcertification'
    version = '1.0.0-SNAPSHOT'
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenCentral()
}

springBoot {
    mainClass = "com.opessoftware.crs.selfcertification.Application"
    layout = "ZIP"
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-web")
    compile("org.springframework.boot:spring-boot-starter-thymeleaf")
    compile("org.springframework.boot:spring-boot-starter-data-jpa")
    compile("org.springframework.boot:spring-boot-starter-mail")
    testCompile("org.springframework.boot:spring-boot-starter-test")
    compile group: 'org.postgresql', name: 'postgresql', version: '9.4.1208.jre7'
    compile group: 'org.apache.commons', name: 'commons-dbcp2', version: '2.1.1'
    compile group: 'junit', name: 'junit', version: '4.12'

}

请注意，如果不是直接尝试运行jarfile，而是systemd 使用Java虚拟机（JVM）从Shell脚本启动 该服务，则该服务将成功运行：

[Unit]
Description=CRS Self-certification Service
Documentation=
Requires=postgresql.service
After=postgresql.service

[Service]
Environment=LOADER_PATH='lib/,config/,/etc/opes/crs/selfcertification'
#ExecStart=/opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar
ExecStart=/opt/opes/crs/selfcertification/startCrsSelfCertification
Restart=always
RestartSec=10
User=crs

[Install]
WantedBy=multi-user.target

Shell脚本/opt/opes/crs/selfcertification/startCrsSelfCertification使用JVM调用jarfile：

#!/bin/sh

java -Dloader.path='lib/,config/,/etc/opes/crs/selfcertification' -jar /opt/opes/crs/selfcertification/crs-selfcertification-1.0.0-SNAPSHOT.jar

Spring Boot jarfile中可能缺少什么，阻止了systemd直接执行jarfile？